So what exactly *is* lapping?
Doc
what lapping is? Is it the combined process of replating the valve and
polishing it down, or just the polishing part?
And why is it called lapping?
Tommy T.
is a question between you and your repairman and is worth asking as the job
can range from rubbing on a little Lava soap to a complex rebore, replate
and polish to fit operation.
The old English definition of "laeppe" was a flap or fold in a garment. In
one definitional direction, this became a specific reference to a flap in a
garment that covered the front part of a seated body and in turn came to
refer to that part of the body itself. In another definitional direction,
it came to mean any sheet of cloth. Eventually sheets of leather which were
used to polish things became know as "laps" and then the word turned into a
verb referring to the act of making using such a sheet to polish something.
The term also means licking your mouthpiece with your tongue. That usage,
however, is an extension of the concept of using the tongue to lift water
into the mouth and derives from the Old English "lapian." Thus we see that
licking your valves may be lapping (in the lapian sense) but is not apt to
be lapping (in the laeppe sense) unless your lapper (in the tongue sense) is
more abrasive than normal.
Tommy T.
"Doc" <docsa...@yahoo.com> wrote in message
news:f0c1bc20.04051...@posting.google.com...
Greg Evans
> ... can someone define exactly what lapping is?
Didn't they outlaw that stuff in L.A.?
Ellestad
between two parts by making the final metal removal a process of the two
parts wearing or polishing against each other. A lapping compound is used to
do the metal removal - this is some form of ultra fine abrasive such as
jeweler's rouge in a lubricant or suspension fluid. This process creates a
super smooth "polished" close tolerance fit, finer than can be produced by
machining, in this case between piston and cylinder. The trick is to know
when to stop. Lapping can achieve the desired smooth finish, perfectly
nested shape between the parts (no piston valve or valve cylinder is truly
perfectly round), and ideal microscopic oil clearance between the piston and
cylinder walls. If the lapping is overdone the fit becomes sloppy - leaky
and sticky and the only reparation will be to have the valves plated and
lapped again.
Undoubtedly the best lapping is the final lapping the valves get when they
are new and being "broken in". The final fit is created by just the surfaces
of the piston and cylinder polishing themselves, metal to metal, in just the
valve oil.
Tim
"Doc" <docsa...@yahoo.com> wrote in message
news:f0c1bc20.04051...@posting.google.com...
Dr. Trumpet
"Greg Evans" <mis...@larkbooks.com> wrote:
No, but five of them have tested positive for HIV and nearly shut the
"industry" down. Oops, wrong lapping!
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Steven J. Ross
:)
Steve Ross